Fructose use by F. nucleatum (ATCC 10953) proved to be different than other sugar use by this organism and was studied in detail. In contrast to previous studies with glucose or galactose, good growth related to fructose use was found without additional amino acid supplementation to the medium. Anaerobic conditions and glutamate use were necessary for substantial incorporation of radiolabeled fructose into washed cell suspensions. The glutamate dependent radiolabeled fructose retained by washed cell suspensions was recovered as a polyglucose storage product whose properties were identical to that resulting from glucose or galactose use by this organism. In the absence of glutamate, fructose was fermented to D(-) lactate, acetate, and butyrate. The glutamate independent fructose metabolism could be aerobic, however, acetate was the only recoverable product. Analysis of the phosphorylated intermediates of the fructose fermentation revealed an Embden-Meyerhoff pathway but there was an accumulation of a hexose monophosphate intermediate by glutamate grown cells which proved to be fructose-1-phosphate (F1P). The presence of F1P and its associated kinase suggests that fructose enters F. nucleatum by a phosphorylation mechanism rather than as the free sugar. Sugar use by other fusobacteria: F. mortiferum (ATCC 25557) grew independently of glutamate but required sugar addition. Several other sugars, in addition to glucose could be used by this organism and inhibition of growth and glucose use was found by adding 2-fluoroglucose to cultures or washed suspensions of the organism. Accumulation of radiolabel from glucose could be demonstrated for this organism, however, the sugar accumulation was glutamate independent. F. russii, F. varium, and F. gonidaformans appear to have glutamate stimulated glucose accumulation similar to that demonstrated for F. nucleatum. No accumulation of glucose was found by washed cells of F. perfoetens, however, there is some evidence that glucose will stimulate growth of the organism.
